Large fonts like my font Pali have a lot of kerning pairs. It is much easier to manage them by splitting the single PairAdjustment_0 subtable into several others. I renamed mine for greater ease of use.

Subtables and afrc.png (11.92 KiB) Viewed 980 times

I arranged Subtable_hyphen at the top so that it appears by default when selecting the Pair Adjustment lookup, because pairs with hyphen are often problematic when generating kerning values with autokern.

Adding a New Subtable for Alternative Fractions
Click on the gears icon to open the Subtable manager, where one can add or sort subtables. I added Subtable_afrc for a simple demonstration.

Subtable Manager.png (5.62 KiB) Viewed 980 times

Editing the Pair Adjustment Lookup

Find Next afrc.png (12.72 KiB) Viewed 980 times

Close the subtable manager and open the Pair Adjustment lookup in the code editor.

Search for "afrc" to find any pairs using alternative fractions.

Select the lookup pairs and cut them to the clipboard

Go to the end of the lookup and paste them into the new subtable

Paste kerning pairs.png (11.7 KiB) Viewed 980 times

Adjusting the Kerning Pairs for afrc

Close the Pair Adjustment lookup and select Subtable_afrc to inspect those pairs. Use the shortcuts Left/Right cursor, Shift+Left/Right cursor, or Ctrl+Left/Right cursor to adjust the selected kerning pair’s value by 10, 100, or 1 funit respectively.

Subtable afrc.png (6.41 KiB) Viewed 980 times

Note that actions like autokern or trim work on the entire lookup, not just on the selected subtable.